The proposed objectives are: 1. To measure temporal changes in the relative avidity of the antibody populations to herpesvirus-associated membrane antigens and to correlate these findings with ADCC titers and disease patterns in both owl monkeys with HVS-induced lymphoma and in humans with NPC. 2. To fractionate serial serum samples from lymphomatous owl monkeys and patients clinically ill with NPC into their separate immunoglobulin classes (IgG, IgM, IgA) and to determine their specific binding to herpesvirus-infected cells, as well as functions of each immunoglobulin class in mediating or blocking ADCC reactions. 3. To investigate the possibility of immune complexes appearing during malignant progression in owl monkeys and the role of such complexes in influencing in vivo and in vitro ADCC reactions. 4. To correlate the qualitative factors determined in this study with existing pathological findings and antibody titers to ascertain the function of humoral antibody in the control of herpesvirus mediated malignancies.